title: Feeding by heterotrophic dinoflagellates and ciliates on the free-living dinoflagellate Symbiodinium sp. (Clade E).
abstract: To investigate heterotrophic protists grazing on Symbiodinium sp., we tested whether the common heterotrophic dinoflagellates Gyrodinium dominans, Gyrodinium moestrupii, Gyrodinium spirale, Oblea rotundata, Oxyrrhis marina, and Polykrikos kofoidii and the ciliates Balanion sp. and Parastrombidinopsis sp. preyed on the free-living dinoflagellate Symbiodinium sp. (clade E). We measured the growth and ingestion rates of O. marina and G. dominans on Symbiodinium sp. as a function of prey concentration. Furthermore, we compared the results to those obtained for other algal prey species. In addition, we measured the growth and ingestion rates of other predators at single prey concentrations at which these rates of O. marina and G. dominans were saturated. All predators tested in the present study, except Balanion sp., preyed on Symbiodinium sp. The specific growth rates of O. marina and G. dominans on Symbiodinium sp. increased rapidly with increasing mean prey concentration < ca. 740-815 ng C/ml (7,400-8,150 cells/ml), but became saturated at higher concentrations. The maximum growth rates of O. marina and G. dominans on Symbiodinium sp. (0.87 and 0.61/d) were much higher than those of G. moestrupii and P. kofoidii (0.11 and 0.04/d). Symbiodinium sp. did not support positive growth of G. spirale, O. rotundata, and Parastrombidinopsis sp. However, the maximum ingestion rates of P. kofoidii and Parastrombidinopsis sp. (6.7-10.0 ng C/predator/d) were much higher than those of O. marina and G. dominans on Symbiodinium sp. (1.9-2.1 ng C/predator/d). The results of the present study suggest that Symbiodinium sp. may increase or maintain the populations of some predators.
authors.affiliation: School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul, 151-747, Korea.
authors.forename: Hae Jin
authors.initials: HJ
authors.lastname: Jeong
authors.forename: An Suk
authors.initials: AS
authors.lastname: Lim
authors.forename: Yeong Du
authors.initials: YD
authors.lastname: Yoo
authors.forename: Moo Joon
authors.initials: MJ
authors.lastname: Lee
authors.forename: Kyung Ha
authors.initials: KH
authors.lastname: Lee
authors.forename: Tae Young
authors.initials: TY
authors.lastname: Jang
authors.forename: Kitack
authors.initials: K
authors.lastname: Lee
mesh_terms: D056893:Alveolata; D016798:Ciliophora / Q000254:growth & development / Q000502:physiology*; D004141:Dinoflagellida / Q000254:growth & development / Q000502:physiology*; D005247:Feeding Behavior
keywords: Growth; harmful algal bloom; ingestion; protist; red tide